Apparatus for heat treating electrodes



March 5, 1935. D. Y. SMITH 1,993,022

APPARATUS FOE HEAT TREATING ELECTRODES Filed Oct. 17, 1929 2 Sheets-Sheet 1 l 4% I 44 ,M

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\NVENTOR 1). Y 5M! TH ATTOR E March 5, 1935. D. Y. SMITH 1,993,022

APPARATUS FOR HEAT TREATING ELECTRODES Filed Oct. 17, 192.9 2 Sheets-Sheet 2 INVENTOR .D. Y SMITH ATTOR E Patented Mar. 5, 1935 APPARATUS FOR HEAT TREATING ELECTRODES Douglas York Smith, East Orange, N. J., assignor to Westinghouse Lamp Company, a corporation of Pennsylvania Application October 17, 1929, Serial No; 400,308

8 Claims. (01. 21913) This invention relates to the manufacture of total amount of high frequency current must be evacuated devices such as radio tubes or the like so regulated as to be sufficient to provide a high and relates more particularly to the operation of frequency field capable of heating a given mass heat treating the electrodes within the tubes by of metal which in the present case would be the the use of a high frequency field. total number of plates disposed in the field. I1 3 5 In the manufacture of radio tubes which in-, a tube is missing at one of the high frequency clude several internal electrodes, as for example p i ions r fi l th n an ov -loa i imp a cathode, control element or grid and an anode upon the anodes or other metallic portions of the or plate, it is necessary after the device is strucremaining tubes with the result that t p turally complete to remove impurities from the ture of the parts is elevated above that necesl0 electrodes particularly the plate. The removal 'sary for degasification and the metallic parts of impurities is accomplished by a heat treatment may be burned or rendered otherwise defective and a convenient and practical method of heat f r th purp e f r wh h r in n d. treating is attained by disposing a coil of wire t S n Obj ct of th p e nt ven ion, there-- about the tube and in passing high'frequency fore, to provide amethod of stabilizing aconstant 15 current through the coil to create a high fre- Ou of g qu y electrical energy for quency field and thus inductively heat the anode duet ely heating a plurality of metallic d sufficiently to drive out the absorbed gases or Another object of t invention is to Provide perform what is termed a degasifying operation. a p u l y of high frequency u on fie ds fO In order to completely degasify a radio tube it d t v y heating a given u er of meta lic 20 is necessary to subject the tube to a plurality of bodies and f r a m i lly i p in in pla successive degasifying operations while the tube of One Of a y, another COInpenSating dy is connected to an exhaust pump so that the delecapable of absorbing an amount of electrical enterious gases will be drawn from the bulb after y equal the displaced odyeach heat treatment. The degasifying operah r j s n v n s w b vid n 25 tion is therefore performed while the devices are 7 from the following description together W h t e on the exhaust machine and in communication mp yine w e, in Which with the vacuum line and in order to attain high 1 is a side v n l v w of a p r i n of speed production a plurality of degasifying dea Sealing-in and eXhauSil machine having th vices are employed for simultaneous disposition present invention applied thereto. 30 over a plurality of tubes, Fig. 2 is a plan view of an exhaust machine The exhaust machine usually consists of a ShOWIl diagrammatically W a high frequency spider having exhaust ports in which the exhaust heater in Operative relation therewith, and tubes of radio tubes are inserted. The spider is is a fragmentary View O a Portion of the moved intermittently and with each movement exhaust mechanism showing means f sin 35 one radio tube passes from a degasifying p iti n a vertical reciprocation of a number of helical so that with each intermittent mo ement of th conductors for movement about the electrodes of machine a degasified tube is ready for removal radio tubes. to be subjected to other manufacturing oper- A practical embodiment of the v ti may,

40 ations. as shown, comprise a high frequency unit 10 40 As above set forth it is essential in order to proa y positioned adjacent to the pa o moveduce devices such as radio tubes at a rate of merit of Sealing-in and exhaust ach ne 11. speed commensurate with other manufacturing The Sealing-in and exhaust machine y operations, to so arrange and organize degasifyelude a Conveyor Spider 12 having a plurality mg devices that they may be disposed over a pluof heads or holders 13 to receive a bulb 14 and 45 rality of tubes simultaneously. a stem or mount 15 of a radio tube.

It has been found, however, that in pra tic it A mount 15 is positioned in a holder and a bulb often happens that the operator fails to insert 14 disposed-Over the mount, Suitable fi being a radio tube into an exhaust port so that hen provided to seal-in or unite the bulb neck and the machine moves it may happen that in tead mount by fusion. After the bulb and mount 60 of the total number of tubes being positioned for have been consolidated and constitute a partially a degasifying operation, one or more may be completed electrical device 15' it is transferred missing. Inasmuch as the several coils of the to an exhaust port 16. A suitable number of degasifying devices are connected in series with exhaust ports are provided and each port con- 5 a constant source of high frequency current the nects with a vacuum pump (not shown). An

exhaust tube 17 of a device is inserted into an exhaust port so that as the conveyor moves the bulbs are evacuated.

The conveyor 12 may be mounted on a central vertical shaft 18 which receives intermittent rotary movement through any suitable mechanism as for example at Geneva drive from any desired source of power as for example a motor (not shown). Mechanism for sealing-in and exhausting bulbs is well known and the present invention is applicable to machines now in common use.

The bulbs and mounts of electrical devices 15' may be loaded on to the conveyor at A and as the conveyor moves in the direction of arrow X, a mount and bulb are positioned in a holder 13. After the mount and bulb have made a complete revolution with the conveyor and have been fused together the device is ready to be positioned in an exhaust port.

The exhaust ports are thus applied with devices and the conveyor moves them to position B or degasifying position at which the electrodes, particularly the anodes or plates 23 are heated to a degasifying temperature by high frequency induction heating, at which time, as above mentioned, the devices are still connected with the vacuum pumpand as the gases are driven from the electrodes they are removed from the bulb.

After degasification the devices move to position C where a tipping-torch 24 is provided to seal off the exhaust tubes and close the bulbs from the atmosphere. This operation being well known in the art, a further description has been omitted. v

For the purpose of completely degasifying the electrodes it has been found desirable to give each device a plurality of heat treatments and the selected construction shows four positions re-. quiring four helical enclosing conductors 25, '26, 27 and 28. These conductors which may be termed heater-elements are connected in series and to a high frequency source of electrical energy such as the unit indicated by the numeral 10.

The provision of a plurality of heater-elements makes it possible to simultaneously heat treat a number of devices and means are provided for raising and lowering the said elements so that with each movement of the conveyor a completely heat treated device will move from a heater element and a device to be heat treated will enter the high frequency zone or field.

The heater-elements are mounted on a crosshead 29 which is secured to a vertical reciprocable rod 31 movable in a guide bearing 32 and having cam followers 33 on its lower end disposed for engagement with a cam 34 secured to a horizontal shaft 35. The shaft 35 is journaled in bearings 36 and 37 and one end thereof is provided with a beveled gear 38 in mesh with a bevel gear 39 secured to the central shaft 18. The cam and gear mechanism may be so arranged and proportioned that the cross-head 29 is lifted during a movement of the conveyor and lowered during the stationary period of the conveyor.

As above described the present construction provides a plurality of high frequency fields and If it happens that one or more devices are not inserted into the exhaust ports then the heaterelements will descend and one or. more of the fields created will have no core or body to absorb perature detrimental to usefulness.

For the purpose of avoiding the above condition the present construction provides each heater-element with means for absorbing energy in the absence of. a radio tube or other device.

As shown more clearly in Fig. 1 the cross-head 29 is provided with an upright or post 41 disposed adjacent to each heater-element. Each post is provided with bracket arms 42 and 43. These arms extend from the posts and terminate in bearings 44 in which slide rods 45 are disposed. The slide rods'may be of insulative material such as glass and are provided with heads 46 at their upper ends and buttons or enlargements 46' at their lower ends. The rods are free to reciprocate vertically on the vertical axis of the heating-elements.

The lower end of each slide rod 45 is provided with an electrical energy absorbing elementor member 47. These electrical energy absorbing elements may be of iron or steel or any suitable heat resisting material. A material such as nichrome, for example, has been found to give satisfactory results. As shown in the drawings each member 47 may be in the form of a wire helix having its ends connected to constitute a closed circuit and having a projection 48 suitably connected as by a spud 49 with the lower end of the rod 45. The members 47 may be provided with buffer pieces 51 preferably of an insulative material such as asbestos.

The slide rods 45 being free to move, normally drop by gravity to position the members 47 in the high frequency fields within the heater-elements. The buttons 46 may be so positioned as to serve as stops to limit the downward movement of the members 47 and hold them in proper relative positions to receive the same heat treatment as would be received by the anodes of electrical devices.

When an electrical device such as a radio tube is in position in an exhaust port of the conveyor and the crosshead 29 descends the upper surface 52 of a bulb 14 contacts with a lower curved surface 53 of the buffer member 51 and since the rod 45 is free to move, the bulb 14 prevents the energy absorbing member 47 from entering the high frequency field.

It will be understood that the members 47 may be designed to absorb an amount of energy equal to that which would be absorbed if a device was in place in a heating element. Thus the high frequency fields are stabilized and the danger of over-heating is removed.

A machine constructed in accordance with the present invention may be operated without the heretofore constant attendance of an operator to adjust the amount of current'supply depending upon the number of devices missing at the high frequency stage.

Although a preferred embodiment of the invention may be shown and described herein it will be understood that modifications may be made therein without departing from the spirit and scope of the invention as set forth in the appended claims.

said body another separate What is claimed is: I

1. An apparatus comprising means for establishing a. high frequency field, means for moving a conductive body capable of absorbing electrical energy into said field, means for supporting another body independent of said first body and capable of absorbing a similar amount oi electrical energy and means for positioning one body in said field to the exclusion of the other body.

\ 2. An apparatus comprising means for establishing a high frequency field, means for moving a. conductive body capable of absorbing electrical energy into said field, means for supporting above body capable of absorbing a similar amount of electrical energy and means for moving one body into said field to the exclusion of the other body.

3. An apparatus comprising means for establishing a high frequency field, means tor moving a conductive body capable of absorbing electrical energy into said field, means for supporting another body independent of said first body and capable of absorbing a similar amount of electrical energy, means for normally. moving one body toward said field and means body to enter said field to the exclusion of the former.

4. An apparatus comprising a conveyor, a plu-' rality of supports on said conveyor to hold vacuum devices, means for establishing a plurality of electro-magnetic fields to receive and inductively heat electrodes in vacuum devi'ces, means for changing the relative positions of said devices and fields to position said devices in said fields, a. plurality of individual electrical energy absorbing bodies, means for normally moving said bodies into said fields and means for interrupting the movement of said bodies upon a change in the relative positions of said devices and fields. r

for causing the other 5. In a machine for degasiiying electrical devices, means for establishing a high irequency field tor inductively heating the electrodes of a predetermined number of said devices to a degasifying temperature, and means for absorbing electrical energy from said field when less than the predetermined number of said devices enter said field.

6. In a machine ior degasifying electrical devices, means ior establishing a high frequency field for inductively heating the electrodes of a predetermined number of said devices to a degasiiying temperature and means for moving an electrical energy absorbing element into said field with less than said predetermined number or devices are positioned for a degasiiying operation.

7. The method or degasiiying an indeterminate number of electrodes by high frequency induction heating which comprises supplying a source of high frequency current and establishing a high frequency field sufilcient to degasiiy a predetermined number of electrodes and in avoiding overheating of electrodes when less than the given number are applied to the high frequency field by substituting for the missing electrodes a body capable of absorbing an amount of electrical energy equal to that which would have been absorbed by the missing electrodes.

8. A machine for inductively heating the electrodes of each of a plurality of vacuum devices for a degasiiying operation comprising means for establishing a plurality of high frequency fields, means tor changing the relative positions or said devices and fields to dispose devices in certain of said fields, a plum 'ty of electrical energy absorbing elements and means for changing the relative positions 0! said elements and said fields to position said elements in fields not occupied by said devices.

DOUGLAS YORK SMITH. 

